An aneurysm is a phenomenon in which the wall of a blood vessel, typically an artery, is abnormally dilated due to weakening of the vessel wall and a bulb or ball shaped space is created connected to the vessel by a neck. Depending upon where in the body the aneurysm is located, a ruptured aneurysm may be fatal.
Until recently, the main treatment of intracranial ruptured and unruptured aneurysms had been to expose the aneurysm in a surgical procedure and to clip the neck of the aneurysm using surgical clips. These open surgical procedures carry a significant degree of morbidity and mortality. Further, some intracranial aneurysms are inaccessible to open procedures due to their locations deep inside the brain tissue.
More recently, aneurysm repair devices have been used to prevent the aneurysm from getting larger and ultimately rupturing. One popular type of minimally invasive treatment is a detachable coil (DC) which is a wire that is packed into the aneurysm through a catheter and then detached from the catheter. The goal of packing enough mass of this wire into the aneurysm is to increase the resistance to flow into the aneurysm. The probability of aneurysm rupture is further reduced if the slow flow into the aneurysm cause the formation of a thrombus which excludes the aneurysm from even more flow. The many shortcomings of this approach include the unpredictable nature of the procedure (thus leaving a number of aneurysms exposed to significant flow), the high number of coils required (which adds to the length and cost of the procedure), and the possible embolization of coils into distal vessels (thereby occluding them). These problems are especially relevant during treatment of aneurysms with wide necks (e.g., aneurysms having a wide connection to the blood vessel).
Many practitioners have attempted to provide an endoprosthetic device for therapeutically treating aneurysms that does not require an open procedure and whose success is not dependent on the configuration of the aneurysm. For example, there have been a number of proposals for placement of an intraluminal graft bridging the aneurysm to isolate the aneurysmal sac from the active arterial duct. However, this method also occludes any small perforator arteries or vessel branches (both inlet and outlet branches) in the area of the aneurysm and thus causes loss of blood flow to the branches.
There is therefore a need in the art for an aneurysm repair device that has good and predictable aneurysm-sealing characteristics while having a minimal effect on the distal vessel as well as small branching vessels around the neck of the aneurysm.